Examples using human systems include its role in enhancing platelet granulocyte aggregate formation in thrombin receptor-activated whole blood when Factor H regulation is disrupted (17, 18), and in promoting red blood cell (RBC) damage in paroxysmal nocturnal hemoglobinuria (PNH) (19), among others [reviewed in (14)]. The gene discussed is F2R; the disease is paroxysmal nocturnal hemoglobinuria.